Method of thermochemically cutting metal



Feb. 18, 1947. M, me 2,415,815

METHOD OF THERMO-CHEMIGALLY CUTTING METAL Filed Aug. 17, 1945 INVENTOR GEORGE M. DEM/N6 ATTQRN EYS Patented Feb. 18, 1947 ivrn'rnon F THERMOCHEMICALLY cu'r'rme METAL George M. Deming, Orange, N. .L, assignor to Incorporated, a corpora- Reduction Company,

tion oi New York Application August 17, 1945, Serial No. 611,043

Claims. (01.148-9) l This invention relates to the cutting of metal 7 by means of oxygen cutting torches. I

The principal object of the invention is to bring about an improvement in the cutting action by the use of supplementary metal introduced into the cutting oxygen jet.

It has already been proposed in the oxygen perforating of material that is not readily oxidizable, such as silicious slag, by means of a lancetype torch, to project finely divided metal, such as iron, into the oxygen stream or onto the material to be perforated to obtain an increase in temperature by the reaction between the oxygen and the metal particles. In such a procedure it has been recognized that the finely divided iron is likely to be pyrophoric and liable to spontaneous combustion in the stream of oxygen, so it has been suggested to use highly compressed air in place of the oxygen.

According to this invention, the oxygen cutting of metal is improved by the use of finely divided iron, or other metal, introduced into the cutting oxygen stream, as hereinafter described; but spontaneous combustion is prevented, not by eliminating the use stream, but by the use of metal particles which have an oxygen-resistant coating.

of oxygen for the cutting 2 I The oxygen cutting jet from the usualtype 0! cutting torch is supplemented by a separate and independent jet of particles of iron, or other 'metal, so directed into the kerf that they meet the oxygen stream far down in the kerf to pro-- 'duce additional heat where it is most needed in cutting thick metal to maintain the metal of the work-piece above kindling temperature throughout its thickness and to insure continuance of the thermo-chemical action all the way through the work-piece, and also to keep the slag sufficiently fluid to flow freely out of the kerf. Projection of the metal particles far down in the kerf in this fashion, being in itself a departure from pre- The method may be performed in several ways.

Finely divided iron, such as iron filings, the particles of which are superficially coated with iron oxide or some other oxygen-resistant substance, such as a silicious material, is projected into the kerf by the torch along with the cutting oxygen stream, or is projected into the cutting oxygen stream after it leaves the torch tip and at a position near the upper edge of the kerf or even slightly higher. In the latter case the position at which the finely divided iron is discharged into the oxygen jet is preferably just in advance of the cutting jet. The momentum of the iron particles is so much greater than that of the oxygen in the cutting jet that only a moderate velocity of the iron particles is required to cause them to enter the cutting jet even if they be introduced very close to the torch tip where the oxygen stream has not had an opportunity to expand to atmospheric pressure. Regardless of how the iron particles are introduced into the oxygen jet, the cutting action is stimulated by the increased temperature obtained by reason of the burning of the iron particles in the oxygen stream.

The use of the supplementary metal makes it possible to cut through metals which do not otherwise readily respond to the oxygen cutting jet (i. e., difiicultly oxidizable). This process also makes it possible to cut through greater thicknesses of metal than heretofore, especially if the supplementary metal is introduced into the oxygen stream far down into the kerf instead of near the upper edge of the kerf as above described.

vious proposals, is part of the present invention, even if the oxygen-resistant coating on the metal particles be omitted when the method is carried out in this way.

The accompanying drawing illustrates the several variations of the method and shows more or less diagrammatically two types of apparatus which may be used in carrying them out.

In the drawing:

Figure 1 is a side elevation, partly in vertical section, of apparatus suitable for carrying out the form of the method in which the metal particles are projected far down into the kerf; and

Fig, 2 illustrates a rearrangement of the apparatus shown in Fig. 1 whereby the form of the method, in which the metal particles are projected into the oxygen stream at the upper edge of the kerf and from a position in advance of the oxygen jet, may be carried out.

' Referring first to Fig. 1, the metal work-piece to be cut is represented at W. The tip of a standard cutting torch, such as an oxyacetylene cutting torch, is shown at T. The tip has the usual passages I for supplying a mixture of fuel gas and oxygen to the preheating flames which are used to bring the metal of the work-piece up to kindling temperature, as is well understood in the art. The tip also has a central passage 2 for supplying oxygen to the cutting jet 3. When the particles are projected into the kerf with the cutting oxygen they pass through this central passage 2. The drawing shows a kerf K partially cut across the work-piece by the oxygen cutting jet.

The work-piece represented in Fig. 1 is assumed to be of greater thickness than can be satisfactorily cut by the usual method of horizontal cutting with the standard cutting torch alone. Metal particles, such as iron filings, the particles of which have an oxygen-resistant coating, as above described, are entrained in a separate jet 4 of oxygen which is projected into the kerf, at such a distance behind the principal oxygen cutting jet, and at such an angle, that the particles reach the oxygen stream at a zone P which is a substantial distance down in the kerf where ad- 3 ditional heat is required to insure continuance of the cutting all theway through the thickness of the work-piece.

The jet 4 of metal particles may be produced in any suitable way. For instance, it may issue from a nozzle N forming part of appropriate apparatus adapted to produce the desired jet. The distance'down the kerf to the zone P where the metal particles should be fed into the oxygen stream will depend upon the thickness of the metal being cut and other things. Ordinarily, it will be at least one-half way down the kerf.

The supplementary metal, when fed into the kerf as just described, reacts with the oxygen stream and generates heat deep in the kerf and promotes the cutting reaction in the region where the purity of the oxygen has been impaired and where additional heat is required to insure continuance of the thermo-cliemical action throughout the thickness of the metal. It. also raises 4 of which have an oxygen-resistant superficial coating of suihcient thicknessto prevent combustion of the metal particles until subjected to the heat of the cutting operation.

2. The method of thermo-chemically cutting metal which comprises directing an oxygen cut-.

ting jet against the metal while the metal is at kindling temperature, and feeding into the oxygen stream finely divided iron the particles of which have an oxygen-resistant superficial coating of sufiicient thickness to prevent combustion of the iron particles until subjected to the heat the temperature of the slag and makes it more fluid so that it can flow more freely from the kerf. Thus, it'is possible to cut much greater thicknesses of metal than heretofore wasipossible by the use of a standard cutting torch a1one'.-=s

In Fig, 2 the nozzle N for, projecting the jet 4' of coated metal particles into the cutting oxy gen stream 3' is shown positioned in advance of the torch tip T and so arranged as to project the metal particles into the cutting oxygen jet ,soo'nafter it leaves the torch tip. Thus, this type f of apparatus is previously described form of the method in which suitable for carrying out the the coated metal particles are introduced into the oxygen jet near the upper edge of the kerf.

While the most suitable metal to use as the supplementary finely divided metal is probably iron or a ferrous metal, the use of any other metal which might be pyrophoric and which can be rendered non-spontaneously combustible by an oxygen-resistant coating on the particles, falls within the invention.

When the metal particles have a silicious coating it may-be such that it reacts with the slag to form a more fluid slag by reason of incorporation of resulting iron silicates. This action may be taken advantage of in cutting thick sections by the form of method illustrated in Fig. 1

to obtain, in the vicinity of the zone P where ahigh degree of fluidity of the slag is especially desirablaeven greater slag fluidity than is produced by the increased temperature brought about by the introduction of the metal particles at this zone. As above stated, however, the projection of metal particles into the kerf in the manner shown in Fig. 1 to make it possible to cut through greater thicknesses of metal than heretofore was possible is considered novel and part of the present invention regardless of whether the metal particles have the oxygenresistant coating.

The-method in its various forms is especially.

useful in on ting oxygen-resistant steels such as high chromium steels and other metals which are ordinarily considered to be difiicult to cut with an oxygen cutting. jet.

I claim: l. The method of thermo-chemically cutting .metal which comprises directing an oxygen cutting jet against .the metal while the metal is at kindling temperature, and feeding into the oxygen stream finely divided metal the particles of the cuttingoperation.

, 3. The method of thermo-chemically cutting metal which comprises directing an oxygen cutting'jet against the metal while the metal is at kindling temperature, and feeding into the oxygen stream finely divided iron theparticles of which have a superficial coating of iron oxide of sufllcient thickness to prevent combustion of the iron particles until subjected to the heat of the cutting op ration.

4. The method of thermo-chemically cutting metal which comprises directing an oxygen cutting jet against the metal while the metal is at kindling temperature, and feeding into the oxygen stream finely divided metal the particles of which have a superficial silicious coating of sufficient thickness to prevent combustion of the metal particles until subjected to the heat of the cutting operation.

5. The method of thermo-chemically cutting through metal work-pieces of heavy section which comprises directing an oxygen cutting jet against the metal while the metal is at kindling temperature, and feeding into the kerf cut by the oxygen jet finely divided metal the particles of which have an oxygen-resistant superficial coating, the finely divided metal being fed into the kerf so that it meets the cutting oxygen stream a substantial distance down in the kerf where additional heat is required to insure continuance of the thermo-chemical cutting action throughout the thickness of the work-piece, and the oxygen-resistant coating on the metal particles being of suficient thickness to prevent combustion of the metal particles until subjected to the heat of the cutting operation.

GEORGE M. DEIEENG.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,286,192 Aitchison June 16, 1942 968,350 Harrison Aug. 23, 1910 1,494,003 Malcher May 13, 1924 FOREIGN PATENTS Number Country Date 455,687 France May 30, 1913 426,990 Germany Dec. 31, 1926 12,225 British Oxygen Oct. '7, 1909 641/26 Australian Feb. 19, 1926 OTHER REFERENCES Metals Handbook, 1939 ed., published by Amer. Society for Metals, Cleveland, Ohio. (Copy in Div. 3.), Page 933. 

